Process of recovering values from sulfid ores.



UNlTED STATES Pa ana: OFFICE.

W EDWin oi ron L1 1, I on mac. mam.

, pnoeess oF nEoov Esme VALUE S FROM SULFIDORES; r

To all whom it may concern:

.Be it known that'I, EDWIN C. PoiILn, a citizen of the United States, residing at Reno, in the county of VVashoe and State of Nevada have invented certain new and useful Im provements in Processes of Recovering Values from Sulfid Ores and l do hereby declareth'e following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art towhich it appertains to make and use the same.

In many parts of the country are found deposits of sulfids containing gold and'silver' associated with base metals, including copper, and which by reason of their low grade complish by a combined dry and wet process which is hereinafter described and claimed.

It is well known that solutions of the cyanids of the alkali metals dissolve both gold and silver as well as co per; but it is found when ores such as are a ove described are 'so treated only a portion of the gold. and silver is dissolved, so much. of the values, mainly silver, remaining in the tailings that the proc ess is not available. I avoid this objection by subjecting the ore to a preliminary treatment by which the metals are transformed into a readily-soluble condition.

In detail my process is as follows: The ore is first crushed to the desired fineness, which will vary according to the ore from four to forty mesh. If the quantity of sulfur in the ore is insuflioient to-theoretically satisfy the reaction, sulfur-bearing material, such as pyrites, is added. The ore is then subjected to a chloridizing-roast with sodium or calcium chlorid. For this purpose the .pulverulentl ore is intimately mixed with, for instance,

common salt, ,suflicient being used to trans form the contained metals into chlorids, as

may be calculated after analysis of the ore.

The mixture is then subjected to-a heat just sufiicient to accomplish the reaction'between the chlorid and the metallic sulfids in an oxidizing atmosphere. This roasting may be Patented an. 3011906.

volving roaster and the heat and flame required for the roasting may be obtained from fuel burning in a fire-chamber c'ommunicatingdirectlysvith the roasting-chamber. The

roasting should be done under a forced draft produced either by a blast or by an exhaust at the outtake, or both. v

It is well known that in all. roastings of oresthere occur losses of values due tovola- .tilization and that in subjecti'ngores to a chloridizingroast .a larger pro ortion of the metals are lost by becoming vo atile chlorids, which pass off with the products of combustion at the temperature of the --roast.- This loss is increased in proportion to the temperature' at which theroast is conducted, and I therefore in practicing my process employ a temperature as low' as is compatible with efiecting the reaction. In order to avoid losses otherwise unavoidable from this source, I pass the products of combustion and the fumes coming from the roasting-chamber through a filter screen or screens by which. the metallic fumes will be collected. These screens Will be formed of textile material which may be maintained in a wet condition by suitable means. The filter-screens will be removed from time to time as they become clogged and the collected values recovered by any of the usualmetallurgical rocesses. After the mixture has been sub ected to .theheat and'oxidation a sufficient time it is withdrawn from the furnace continuously or intermittently and allowed to cool, and during the cooling it will be found that the reaction will continue if the mass still contains any unchanged metallic sulfids.

The reason win the gold chlorid is not dis solved or washe out with the copper when i the ore is leached with water is that the absence of auric chlorid'in the productof the chloridizing-roast is that it forms at a terns pcrature not to exceed 280 Fahrenheit; but as the temperature increases it is practically decomposed, being completely transformed into aurous chlorid at about 347 Fahrenheit; On increasing the temperature to about 392- Fahrenheit the aurous chlorid will be completely reduced to metallic gold.

Moreover, in the chloridizing-roast ferric sulfate FeSo will form, which acts as a reducing agent on gold chlorids. It willbe seen, therefore, that at the temperature at which the chloridizing must be carried any auric chlorid formed in the earlier stages will be completely reduced by the higher temperatures of the latter stages of the process and that if by any chance any gold chlorid remained in the roasted ore it-would be reduced by theFeSo present on the addition of water.

After the ore has cooled it is transferred to a filtering-tank and preferably leached with water. The water Wlll dissolve out any copper present, which subsequently will be re- 7 covered by any desired metallurgical procsufiicient for a comphate sciution of the gold,

ess. The water will dissolve also other metallic chlorids, except gold and silver, the.

sodium sulfate produced in the roast, and especially any acid bodies which may be contained in the roasted ore, the presence of which will cause waste of the cyanid solution subsequently used. The leaching with .wa-

residue after the leaching with water, or, if that be omitted, the cool ore directly from the chloridizing-roast, is subjected to the ordinary cyanid process for the recovery of the gold and silver. I have found that afterleaching with Water a solution of-potassium cyanid of 0.2 per cent. to 0.4 per cent. strength is and silver, the leaching being conducted in the usual manner, and from the resulting solution the gold and silver may be precipitated by zinc or in any desired way.

I claim- 1. The processof recov erin values from sulfid ores containing gold, and silver, which consists in mixing the ore with a chlorid, subjecting the mixture to heat in an oxidizing atmosphere, cooling the product, leaching the mass with water, to remove the contained bodies soluble therein, leaching the residue with a solution of a cyanid of an alkali metal, and, finally, precipitating the gold and silver from the solution.

2. The process of recovering values from sulfid ores containing gold and silver, which consists in mixing the ore with a chlorid sub jecting the mixture to the flame of combustion with an excess 'of air, conducting or? the gaseous products, condensing and collecting the metallic vapors, cooling the solid products, leaching the mass with a solution of a cyanid of an alkali metal, and precipitating the gold and silver from the solution, substantially as described 3. The process of recoverin values frd'm oo sulfid ores containing gold, silver and base metals, which consists in mixing the ore with a chlorid, subjecting the mixture to the flame of combustion with an excess of air, conducting off the gaseous products, condensing and collecting the metallic vapors, cooling the solid products, leaching the mass with water to remove the contained bodies soluble therein, leaching the residue with a solution of a cyanid of an alkali metal and recipitating. the gold and silver from the soution, substantially as described. 4. The process of recovering values from sulfid ores containing gold and silver which consists in mixing the ore with a chlorid, subjecting the mixture to the flame of combustion with an excess of air, conducting'off the gaseous products, condensing and collecting the metallic vapors, cooling the solid products, leaching the mass with a solution of 'a cyanid of an alkali metal and precipitating the gold and silver from the solution sub stantially as described.

5. The process of recovering values from sulfid ores containing gold and silver which consists in mixing the ore with a chlorid, subjecting the mixture to heat in an oxidizing temperature, cooling the product, leaching the mass with water to remove the contained bodies soluble therein, leaching the residue with a solvent of gold and silver, and finally pr c pitating the gold and silver from the solution.

6. The process of recovering values from sulfid ores containing gold and silver, which consists in roasting the ore in contact with the flame of combustion with an excess of air, conducting oh" the products of combustion and resulting vapors by a forced draft, condensing the metallic vapors and filtering them from the permanent gases, substantially as described.

7. The process of recovering values'l'rom sulfid ores containing gold and silver, which consists in mixing the ore with a chlorid, subj ecting the mixture to the flame of combus tion with an excess of air, conducting off the products of combustion and resulting metallic vapors by a forced draft, condensing the metallic vapors and filtering them from the permanent gases, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. v l

EDWIN C. POI-Illa.

Witnesses:

NALTER J. HAnms, A. v P. Limonx. 

